function makeIds () {
  var content = document.querySelector('.js-toc-content')
  var headings = content.querySelectorAll('h1, h2, h3, h4, h5, h6, h7')
  var headingMap = {}

  Array.prototype.forEach.call(headings, function (heading) {
    var id = heading.id ? heading.id : heading.textContent.trim().toLowerCase()
    .split(' ').join('-').replace(/[!@#$%^&*():]/ig, '').replace(/\//ig, '-')
      headingMap[id] = !isNaN(headingMap[id]) ? ++headingMap[id] : 0
      if (headingMap[id]) {
        heading.id = id + '-' + headingMap[id]
      } else {
        heading.id = id
      }
  })
}
